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PS 6 questions??


S

Sark

Power User
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Hi all

First a couple of quickies.

1...Is it possible to purge RAM in PS6.

2...I can reset the default palette locations but, can I reset (reposition) just those that are currently available.

And one slightly longer.

3...If I upsample by 400% using "nearest neighbour", then zoom to 25%, the image is identical to the original (viewed at 100%). Fine, I understand this but, if I upsample by 400% using "bicubic", then zoom to 25%, the image is still identical to the original (viewed at 100%).

If bicubic changes the image, why does the 25% zoomed image not appear different to the original when they're both the same size on screen. Does zoom remove exactly the same pixels that bicubic upsampling added ???

Sark
 
(PSD) Sergiy

I`m not sure that i can help with that... but i know exactly, that
if you zoom, its ain`t gonna hurt a picture at all... at least you
saved it after.
Bicubic? I dont realy understand what you mean by that? :)
 
Hi Sark...

#1) Look under the EDIT menu, near the bottom.

#2) Just drag the visible palettes anywhere you want within the work area. Once positioned, they'll stay where they are until you change them again or your PS Prefs gets reset.
There's an option in the Prefs to get PS to remember the palette locations from session to session. I believe it's truned on by default.

#3) The question is mute. You should never upsize an image by any large degree, especially by 400%.
But so you know... if i remember correctly, PS uses the Bicubic interpolation method when zooming. So that may explain why it looks the same.

:B
 
thekeeper, thanks for posting.

1...I'm not at my own pc right now but I remember there is an option to purge History, Undo and All, but nothing about RAM
When I upsampled the image by 400% my memory in task manager jumped to over 300mb and remained there even after closing the image???

3...This was just an excercise I did while comparing Shortcut's S-Spline (an interpolotion tool) with PS's bicubic resampling. It just seemed odd that the image is technically different after resampling but reverts back to the original when zoom removes pixels. As you say, all academic really.

Sark
 
Sark, you just cannot compare the way you did, and this for one simple reason: when Photoshop or any other app zooms out to 25%, it simply shows one out of four pixels. And this for the very simple reason that it is your operating system that decides how many pixels there are on you screen. The screen size being a fixed size, your os decides how large each pixel is.
So when Photoshop n,eeds to make something 25% smaller ON THE SCREEN USING THE ZOOM TOOL, it simply does not show the unnecessary pixels. Which is why the image is always of a bad quality.
When it has to resample, it will recalculate the existing pixelmap to add the necessary pixels, or, in case of downsapling, discard of a number of pixels and recalculates the others.

If you really need upsampling, and you may want to avoid it at all costs, do so in several small steps. These small steps are also adviseable for downsampling, yet that does work a tad better.

But whatever: you do influence the original data, and a lot of original information will be lost. So, if possible: rescan, or starta new. Or, if not otherwise possible: start too large, and downsample.
 
I can see where you're coming from Eric. I just assumed if the whole image had changed with bicubic upsampling then 25% of those image pixels should also be different.
I suspect PS is just discarding the same pixels that it added when upsampled, hence it appears the same as the original when viewed on screen.

Anyway, it's academic now. When I first tested the s-spline tool I was quite impressed but, after looking closer it really only cheats to improve on PS's bicubic.
Basically it creates hard edges where there is a strong contrast. This gives a sharp, but unnatural, look to the image and could probably be achieved with other PS tools if desired.

I'm just about to buy a 2 meg pix camera which will be fine for most of my requirements. I never intended on upsampling by 400% but was just experimenting to see what I could achieve for the occasional larger print.

As for the purge problem, I still can't solve this. I'm still having to close PS to clear RAM... :(

Sark
 
Should yopu use copy and paste, and there is info on the clipboard which takes immobilizes ram, you can create a new doc of one by one pixel, and copy that to the clipboard.

Which os are you using?
 
I've now "kind of" solved this. Basically RAM "is" being purged when an image is closed but, the Task manager is not responding to this.
If Task manager shows 200mb memory usage, when I close the image I can open a new image and keep building the file size without adding to the 200mb figure in Task manager. Only when total memory usage surpasses 200mb will it begin to change.

I'm using Win 2K but, because closing PS resets the Task managers memory reading I must assume PS is at least partly responsible.

I'm not really too concerned now, as this is just an incorrect reading issue rather than something than can limit PS's memory usage.

Thanks for the replies, it's much appreciated.

Sark
 
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